1. Field of the Invention
The present invention generally relates to treating sleep disorders, and more specifically relates to methods and devices for treating patients suffering from obstructive sleep apnea and hypopnea.
2. Description of the Related Art
Obstructive sleep apnea (OSA) is caused by a blockage of the airway, which usually occurs when the soft tissue in the throat collapses and closes during sleep. During each apnea event, the brain briefly arouses the sufferer in order to initiate the resumption of breathing, however, this type of sleep is extremely fragmented and of poor quality. When left untreated, OSA may result in high blood pressure, cardiovascular disease, weight gain, impotency, headaches, memory problems, job impairment, and/or motor vehicle crashes.
According to the National Institutes of Health, OSA is rather common and affects more than twelve million Americans. OSA affects males more than females. Other risk factors include being overweight and over the age of forty, however, OSA can strike anyone at any age, even children. Despite the seriousness of OSA, a lack of awareness by the public and healthcare professionals results in the vast majority of patients remaining undiagnosed and untreated.
There have been a number of efforts directed to treating OSA. For example, devices for electrically stimulating the soft palate to treat snoring and obstructive sleep apnea are disclosed in U.S. Pat. Nos. 5,284,161 and 5,792,067. These devices have had mixed results because they require patient adherence to a regimen of use, subject the patient to discomfort during sleep, and result in repeated arousal of the patient.
Another protocol for treating OSA, continuous positive airway pressure (CPAP), delivers air into the airway through a specially designed nasal mask or pillow. The flow of air creates positive pressure when the patient inhales to keep the airway open. CPAP is considered by many to be the most effective non-surgical treatment for the alleviation of snoring and obstructive sleep apnea, however, patients complain about discomfort from the mask and hoses, including bloating, nasal drying, and dry eyes. As a result, patient compliance is only about 40%.
Surgical treatments have also been employed. One such treatment is referred to as uvulopalatopharyngoplasty, which involves removing about 2 cm of the trailing edge of the soft palate to reduce the soft palate's ability to flutter between the tongue and the pharyngeal wall of the throat. The procedure has been effective in alleviating snoring, but is painful and frequently results in undesirable side effects. In particular, removal of the trailing edge of the soft palate compromises the soft palate's ability to seal off nasal passages during swallowing and speech. As a result, many uvulopalatopharyngoplasty patients experience fluid escaping from the mouth and flowing into the nose while drinking.
Another procedure uses a surgical laser to create scar tissue on the surface of the soft palate. The scar tissue reduces the flexibility of the soft palate, which, in turn, reduces snoring and/or closing of the air passage. The above-mentioned laser procedure may have limited utility in treating snoring, but is ineffective in treating OSA.
Cautery-assisted palatal stiffening operation (CAPSO) is a recently developed office-based procedure performed with local anesthesia. A midline strip of soft palate mucosa is removed, and the wound is allowed to heal. The flaccid palate is stiffened, and palatal snoring ceases. As with the previously discussed surgical approaches, this procedure is not effective in treating OSA.
Surgical procedures such as uvulopalatopharyngoplasty and those mentioned above continue to have problems. The area of surgical treatment (i.e., removal of palatal tissue or scarring of palatal tissue) may be inappropriate to treat the patient's condition. In addition, the proposed procedures are painful with extended and uncomfortable healing periods. For example, scar tissue on the soft palate may present a continuing irritant to the patient. Moreover, the procedures are not reversible in the event they happen to induce adverse side effects. Finally, the procedures are useful in some patients experiencing snoring, but have little beneficial effect on patients with OSA.
Other surgical approaches have been tried that employ the use of RF or microwave energy (Somnoplasty) to shrink tissue in the tongue or soft palate. Radiofrequency ablation of the soft palate is used to produce thermal lesions within the tissues. Somnoplasty devices have been approved by the U.S. Food and Drug Administration (FDA) for radiofrequency ablation of palatal tissues for simple snoring and for the base of the tongue for OSA. In some situations, radiofrequency of the soft palate and base of tongue are performed together as a multilevel procedure. To date, the treatments alone or in combination have failed to provide relief to more than 50% of patients.
Another device intended to treat snoring or obstructive sleep apnea uses several braided PET cylinders that are implanted to make the tissues of the tongue or uvula more rigid and less prone to deflection. The Pillar™ Palatal Implant System sold by Restore Medical of St. Paul, Minn. is an implantable device that has been cleared by the FDA. The device is a cylindrical-shaped segment of braided polyester filaments that is permanently implanted submucosally in the soft palate, for reducing the incidence of airway obstructions in patients suffering from mild to moderate obstructive sleep apnea. The Pillar device has been associated with a number of adverse side effects, including extrusion, infection, and patient discomfort.
Another implant system sold under the trademark REPOSE™ by InfluENT of Concord, N.H., uses a titanium bone screw that is inserted into the posterior aspect of the mandible at the floor of the mouth. A loop of suture is passed through the tongue base and attached to the mandibular bone screw. The Repose™ procedure achieves a suspension, or hammock, of the tongue base making it less likely for the base of the tongue to prolapse during sleep. Due to the high activity of the tongue during wakefulness, the suture component of this device may act as a “cheese cutter” to the tongue, causing device failure and requiring subsequent removal.
One effort for treating OSA involves creating an auxiliary airway. In one embodiment, commonly assigned U.S. patent application Ser. No. 12/182,402, filed Jul. 30, 2008, the disclosure of which is hereby incorporated by reference herein, teaches forming an auxiliary airway for treating obstructive sleep apnea by implanting an elongated conduit beneath a pharyngeal wall of the pharynx. The elongated conduit has a proximal end in communication with a first region of the pharynx, a distal end in communication with a second region of the pharynx, and a section extending beneath the pharyngeal wall for bypassing an oropharynx region of the pharynx.
Magnets have also been used for treating sleep apnea. For example, in one embodiment, commonly assigned U.S. patent application Ser. No. 12/183,955, filed Jul. 31, 2008, the disclosure of which is hereby incorporated by reference herein, discloses a magnetic implant including a bone anchor, a first magnet coupled to the bone anchor, a tongue anchor, a second magnet coupled to the tongue anchor, and a support for aligning the first and second magnets so that a repelling force is generated between the magnets for urging the second magnet away from the first magnet and toward the bone anchor. The support maintains the first magnet at a fixed distance from the bone anchor, aligns the first magnet with the second magnet, and guides movement of the first and second magnets.
In spite of the above advances, there remains a need for additional methods and devices for reducing the burden of managing obstructive sleep apnea through minimally invasive approaches that provide long term results, that encourage patient compliance, and that minimize patient discomfort.